In recent years, optical analysis techniques have been developed for a number of applications. Some of these techniques employ the use of a thin-film optical interference element, also known as a multivariate optical element (“MOE”). In general, these techniques optically interact electromagnetic radiation (e.g., from a sample) with the MOE, wherein the output reflects the measured intensity of the electromagnetic radiation. The measured intensity may then be utilized in a number of applications, such as, for example, sensors.
Historically, such thin-film optical elements have been designed and fabricated using alternating layers of high-index and low-index materials deposited on a substrate. Once the materials have been deposited on the substrate, however, the transmission/reflection/absorption functions of the thin-film optical element are fixed due to the fundamental nature of the design and fabrication process. Therefore, once the film stack has been deposited, its spectral properties cannot be changed.